1. Field of the Invention
The present invention relates to an industrial robot hand-holding device and in particular to a hand-holding device of the type having therein a safeguard unit for preventing the robot arm and the robot wrist of the industrial robot, as well as the essential components of the hand-holding device, from being broken.
2. Description of the Prior Art
A conventional industrial robot is provided, at the extremity of the arm or the wrist thereof, with a robot hand which is controlled by a robot control device and is widely used in various industries as a laborsaving device. Particularly, conventional industrial robots are being utilized more and more in combination with a machine tool for carrying a workpiece, for loading and unloading a workpiece, for carrying a workpiece after machining, and for assembling various parts. Recently, there has been provided an interchangeable robot hand type of industrial robot, namely, an industrial robot capable of sequentially executing desired robot task by alternately holding a robot hand, selected from among a plurality of robot hands previously prepared for a specific purpose, at the extremity of the arm and the wrist thereof. Such an interchangeable robot hand type of industrial robot is provided with a hand-holding device at the extremity of the arm or the wrist thereof and is adapted to execute desired robot task by alternately and detachably holding various robot hands by means of the hand-holding device. A previously proposed hand-holding device is provided, at the extremity thereof, with a receiving hole formed in the shape of a tapered hole for receiving an attaching part of a pull stud, formed in a robot hand, in order to hold the robot hand. The hand-holding device, in general, is permanently fixedly connected to the extremity of the robot arm or wrist. In such an interchangeable robot hand type of industrial robot, it is possible that the application to the robot hand of an extraordinary external force, such as an unexpected external force or a shock, resulting from malfunction of the robot during operation or the sudden starting of the robot in response to external noise signals may affect and damage not only the robot hand but also the hand-holding device, the robot arm, and the robot wrist.